Flat panel optical display systems, such as liquid crystal displays, are well known and widely used. Many such displays (e.g., liquid crystal displays) require polarized illumination light. Typically, polarization of illumination light greatly attenuates the light, thereby resulting in displays with decreased brightness, or require relatively expensive optical components. Moreover, such displays commonly have relatively low contrast ratios, which decreases image clarity and overall image quality. Furthermore, such displays typically require complex or difficult manufacturing processes.
To address such shortcomings, the present invention includes a microelectrical mechanical optical display system that employs microelectrical mechanical system (MEMS) actuators to modulate light. As is known in the art, MEMS actuators provide control of very small components that are formed on semiconductor substrates by conventional semiconductor (e.g., CMOS) fabrication processes. MEMS systems and actuators are sometimes referred to as micromachined systems-on-a-chip.
In one implementation, a MEMS optical display system according to the present invention includes an illumination source for providing illumination light, a collimating lens for receiving the illumination light and forming from it collimated illumination light, and a converging microlens array having an array of lenslets that converge the collimated illumination light. The converging microlens array directs the illumination light to a microelectrical mechanical system (MEMS) optical modulator.
The MEMS optical modulator includes, for example, a planar substrate through which multiple pixel apertures extend and multiple MEMS actuators that support and selectively position MEMS shutters over the apertures. A MEMS actuator and MEMS shutter, together with a corresponding aperture, correspond to a pixel. The light from the converging microlens array is focused through the apertures and is selectively modulated according to the positioning of the MEMS shutters by the MEMS actuators, thereby to impart image information on the illumination light. The light is then passed to a diffused transmissive display screen by a projection microlens array.
In alternative implementations, a MEMS optical device module can be formed with at least, for example, a converging microlens array, a MEMS optical modulator, and a projection microlens array. MEMS optical display systems according to the present invention can be formed from multiple such modules that are arranged in arrays and combined with light sources, collimating optics, and display screens.
A MEMS optical display system according to the present invention is operable without polarized illumination light, thereby eliminating the light attenuation or expense of the polarizing illumination light. In addition, light can be completely blocked or modulated by the opaque MEMS shutters, thereby providing display images with very high contrast ratios. Furthermore, such MEMS optical modulators can be manufactured by conventional CMOS circuit manufacturing processes.
Additional objects and advantages of the present invention will be apparent from the detailed description of the preferred embodiment thereof, which proceeds with reference to the accompanying drawings.